Treatment of hydrocarbon oils



Patented June 30, 1936 UNITED STATES TREATMENT OF HYDROCARBON OILS Seymour W. Ferris, Aldan, Pa., assignor to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Application March 28, 1933, Serial No. 663,243

20 Claims.

The present invention relates to the art of mineral oil refining, and has particular reference to the separation of crude petroleum or petroleum products into fractions of different chemical composition while of approximately the same distillation range.

In accordance with my invention, crude petroleum or petroleum products, particularly oils of substantial viscosity, are separated into various fractions by means of fractional extraction with an aliphatic keto-ester, and more particularly ethyl acetoacetate, or a mixture of solvents containing substantial amounts of aliphatic ketoesters.

It is recognized in the art that mineral oils, such as petroleum, comprise essentially a mixture of hydrocarbons of various groups or homologous series of compounds, such for example, as paraffins of the general formula CnH2n-1-2, olefins of the general formula CnHZn, hydroaromatics and polymethylenes of the same empirical formula, and various other series of compounds of chain and/ or ring structures in which the hydrogen to carbon ratio is less than in the foregoing series. A large 25 number of individual compounds of each series and of differing boiling points are present in petroleum.

The various types of crude petroleum, which are generally classified into three groups, namely, parafiinic base, naphthenic or asphaltic base, and mixed base, contain the various series of hydrocarbons mentioned heretofore in different proportions. For example, in the paraffin base crude oils, such as those obtained from the oil fields of Pennsylvania, there is a relatively high proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereas in the naphthenic or asphaltic base crude oils, there is a relatively large proportion of hydrocarbons having ring structures and alow hydrogen to carbon ratio. Mixed base crude oils, such as are obtained from the Mid-Continent oil fields, contain hydrocarbons in proportions intermediate these two extremes.

The variance in the proportion of the different series of hydrocarbons in paraflinic, naphthenic, and mixed base oils is evidenced by the physical properties of the-various oils and particularly by the relationship of the specific gravity to the viscosity of one oil as compared with another. For example, oils derived from a Pennsylvania crude and having a viscosity of 400 seconds Saybolt universal at 100 R, will show a specific gravity at 60 F., of about 0.878, whereas an oil of corresponding viscosity produced from a naphthenic crude, such as one from the Gulf Coast area, will show a specific gravity of about 0.933 at 60 F. The relationship between the viscosity and gravity indicates the degree of parafiinicity or naph thenicity of the oil, and such relationship may 10 log (V38), or G=0.24+0.755a+0.02210g (V'35.5),

in which G is the specific gravity at 60 F., V and V are respectively Saybolt universal viscosities at 100 F. and 210 F., and a is a constant known as the viscosity-gravity constant. Viscous fractions from each of the different types of crude have different viscosity-gravity constants. While, in general, viscous fractions from a single crude have substantially the same viscosity-gravity constant, such constant is lower for fractions of the parafiinic crudes than is the constant for fractions of the naphthenic crudes. An article entitled The viscosity-gravity constant of petroleum lubricating oils by J. B. Hill and H. B. Coats, which will be found in volume 20, page 641 et seq., Industrial and Engineering Chemistry for June 1928, explains the determination of such constant for several typical oils.

The viscosity-gravity constant is, therefore, an index of the paraffinicity or naphthenicity of viscous oils, since when a given crude is distilled, the fractions thereof collected, and the specific gravity and the viscosity of each of the viscous fractions determined, such specific gravities and viscosities substituted in the formula, and the viscosity-gravity constants of the fractions calculated, it will be found that such constants are substantially the same.

The viscosity-gravity constants of the viscous fractions for some of the typical crudes are as follows:

Milltown (Pennsylvania) 0.8067 Burbank (Mid-Continent) 0.8367 Guadalupe (Gulf Coast) 0.8635 Mirando (Gulf Coast) 0.9025

While the above figures indicate the viscositygravity constants of specific oils from several types of crudes, it is to be understood that for any particular type of crude such constant may be within a range between values above and below the constant of the typical crude given. For example, viscous oils resulting from the distillation of Mid-Continent crudes have viscositygravity constants ranging from about .835 to about .855, whereas the viscous fractions resulting from the distillation of Pennsylvania type crude range from about .805 to about .828, and in most instances, are below .820. Oils are increasingly paraflinic as their viscosity-gravity constants de-.

crease 'My invention is based upon the discovery that oils containing both the paraflinic series of hydrocarbons and the various naphthenic'series may.

be fractionally extracted with an aliphatic keto ester. The various series of hydrocarbons possess a differential solubility in such solvent, 4 the naphthenic hydrocarbons being-much more so1uble therein than the parafiihic hydrocarbons; By

means of extraction with such solvent, it is therefore possible to efiect a partial'separation of the naphthenic hydrocarbons from the parafiinic, and to obtain from an oil containing both classes of hydrocarbons, an oil which is much more paraf finlcitl'ianthe original oil and one which is much more naphthenic. By my invention, for example, it isp'ossible'toproduce'ian oil of the quality normally' obtained from" Appalachian crudes, from crudesofthe mixed base type from the Mid-Continent'iarea, and, conversely, to obtain oils from mixed base crimes such as are normally obtained from the naphthenic oils of the Gulf Coast area. In general, from oils from any source there may be obtained by my process, oils which are respectively more paraffinic and more naphthenic than the oils normally obtained fromsuch source by distillation. r

In accordance with m'y'invention, I first mix the oil to be: treated with a suitable proportion of'aliphatic keto-ester" at a temperature such that complete solution is effected'and a homogeneous liquidobtained. I then cool the mixture to a temperature at which separation of the liquid intoa two layer system will take place. The upper'layer will contain a relatively small'amount of the solventdissolved in the paraffinic portion of'the oilwhile'the lower layer will contain the more naphthenic portion of the oil dissolved 'in the solvent; Or, I may agitate "the mixture of solvent and oil at temperatures'at which the liquids arefonly partially miscible, and thereby effect'solution of 5 the naphthenic portionof the oil inpthe solvent; In'either of the'above pro cedures I may take advantage of'the principles of countercurrent' extraction. After the extraction proper, I effect separation of'the two layers which form, by any suitable procedure, 'asfor'example, by decantation. Ithe n remove from each of the separated layers; the portion of solvent which each contains'b'ysuitable procedure, such as by vacuum distillation, thereby toobtain twooils of similar distillation ranges but of different chemical" compositions and different physical characteristics. 7

Before removing the solvent from the upper and more paraffinic layer, I may add a further quantity of solvent and repeat the extraction,

thereby to remove additional-naphthenic constituents from said layer. The extraction step may be repeated any desired number of times, each repetition producing an oil of higher paraf finicity as evidenced by its lower viscosity-gravity constant;

Wheresubstantial quantities of waxy hydrocarbons belonging to the true p-araflin series (CnH2n+2)- are present; such hydrocarbons re-I invention, dewaxing may be effected either prior or subsequent to extraction.

My invention will be further understood from the following specific example:

100 parts of a Mid-Continent distillate having a viscosity of 305 seconds Saybolt universal at 100 F., aspecificgravity of 0.909 at F., and a viscosity-gravity constant of 0.853 was mixed with 300 parts ofethyl a'cetoacetate and heated to slightly above the temperature of complete miscibility,f which was approximately 100 C. The homogeneous liquid which resulted was cooled with agitation to C., and allowed to settle, whereupon. a two layer system formed. After separation, the layers were each freed of solvent by vacuum'distillation. Theeundissolved oil fraction comprising 57I6 of the stock hada viscos ity-of 23'25seconds Saybolt universal at F; a specific gravity of 0.884, and a'viscosity-gravity constant of"0'.827. The dissolved o-il fraction comprising 42.4% of the stock had a viscosity or 488 seconds Saybolt universal at 100 F., a specificgravity of 0.938 anda viscosity-gravity const'ant of 0.890: Y a

- From the above example'it will-be-noted that by-extraction of'an oil with ethyl acetoacetate, there may be obtained oilfractions which are respectively more paraflinic and more naphthenic than the original oil. By repetition of the extraction process upon the undissolved fraction, oils of even greater paraflinicity will result.

My process is practically independent of the solvents have been sense to includeone or a mixture of aliphatic ketO-esters, or a mixture of solvents containing substantial amounts of aliphatic keto-esters. I

Also,,when herein and in theappended claims; oil, is specifically referred to as being viscous,-it isto be understood that the oil is of substantial viscosity,\i..e., of the order of 50 seconds -Saybolt universal at 100" F., or more.

What I'claimis:

1. Inthe art*ofrefining;mineral oils, the process-which.comprises'separating an oil containing parafiinic and naphthenichydrocarbons into fractions respectively richer in paraffinicand naph= thenic compounds by'extractingsaid oil with an aliphatic'keto-ester.

2. Inthe art of refiningmineral'oils, the process Whichcomprises adding an aliphatic keto-ester to an oil containing. parafiinic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solution to form'a two-layer system, and separating the upperlayer from the lower layer. s v

' 3. In the artof'refining mineral oils, the'process which comprises adding an aliphatic ketcester to an oil containing paraflinic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solution to form. a two-layer system, removing, the

lower layer, and similarly retreating the upper layer with an aliphatic keto-ester.

4. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing parafiinic and naphthenic hydrocarbons into contact with an aliphatic keto-ester thereby to effect solution of a portion richer in naphthenic hydrocarbons in the aliphatic keto-ester, separating the solution so formed from the remainder of the oil, and removing the said keto-ester from both portions of the oil, thereby to obtain fractions of the oil respectively richer in parafiinic and naphthenic hydrocarbons.

5. The process for separating mineral oils containing parafiinic and naphthenic hydrocarbons into fractions which comprises bringing the oil into contact with an aliphatic keto-ester thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in the aliphatic ketoester, separating the solution so formed from the 'remainder of the oil, and distilling the aliphatic keto-ester from both of the portions of the oil, thereby to obtain fractions of the oil respectively richer in parafiinic and naphthenic hydrocarbons.

6. The process of treating a viscous fraction of a crude oil of one type containing parafiinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different type having a greater content of paraflinic hydrocarbons which comprises extracting the viscous fraction with an aliphatic keto-ester, and separating the oil so treated into portions respectively richer in paraflinic and naphthenic hydrocarbons.

7. In the art of refining mineral oils, the process which comprises bringing an aliphatic ketoester into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing paraflinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic components, thereafter removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby to produce an oil such as is normally obtained from Pennsylvania type crude by distillation.

8. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing parafiinic and naphthenic hydrocarbons into contact with an aliphatic keto-ester thereby to effect solution of a portion richer in naphthenic hydrocarbons in said keto-ester, separating the solution so formed from the remainder of the oil, and retreating the oil remaining with additional amounts of an aliphatic keto-ester.

9. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing parafiinic and naphthenic hydrocarbons into contact with ethyl acetoacetate, thereby to effect solution of a portion richer in naphthenic hydrocarbons in the ethyl acetoacetate, separating the solution so formed from the remainder of the oil, and removing the ethyl acetoacetate from both portions of the oil, thereby to obtain fractions of the oil respectively richer in paraflinic and naphthenic hydrocarbons.

10. The method of producing parafiinic lubricating oil from mixed base crude which comprises distilling the crude and bringing a portion thereof into contact with ethyl acetoacetate, thereby partially dissolving the oil, separating the ethyl acetoacetate solution of oil so treated, and removing the ethyl acetoacetate from the treated oil.

11. In the art of refining mineral lubricating oil containing paraflinic and naphthenic hydrocarbons, the step of fractionally extracting the oil with ethyl acetoacetate, to effect a separation of fractions respectively richer in parafiinic and naphthenic compounds.

12. The process of treating a viscous fraction of a crude oil of one type containing paraffinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of difierent type having a greater content of paraifinic hydrocarbons, which comprises extracting the viscous fraction with ethyl acetoacetate and separating the oil so treated into portions respectively richer in paraffinic and naphthenic hydrocarbons.

13. The process of treating a viscous fraction of a mixed base crude oil to procure a fraction having the quality of a corresponding fraction of a paraffinic base crude, which comprises extracting the viscous fraction with ethyl acetoacetate, and separating the oil so treated into portions respectively richer in paraffinic and naphthenic compounds.

14. In the art of refining mineral oils, the process which comprises adding ethyl acetoacetate to a viscous oil liquid at ordinary temperatures containing paraffinic and naphthenic hydrocarbons, heating the mixture to a temperature sufficient to effect solution, cooling the solution to a temperature sufiicient to form two layers respectively richer in naphthenic hydrocarbons and parafiinic hydrocarbons other than wax, and separating the upper layer richer in parafiinic hydrocarbons from the lower layer richer in naphthenic hydrocarbons.

15. In the art of refining mineral oils, the process which comprises bringing ethyl acetoacetate into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing paraffinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic com-- ponents, thereafter removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby to produce an oil such as is normally obtained from Pennsylvania type crude by distillation.

16. The process of decreasing the viscositygravity constant of a viscous mineral oil which comprises extracting the oil with an aliphatic keto-ester.

17. The process of decreasing the viscositygravity constant of a viscous mineral oil at least 0.015 which comprises extracting the oil with ethyl acetoacetate.

18. The process of treating a viscous mineral oil of viscosity-gravity constant between substantially 0.850 and 0.875 to reduce the viscositygravity constant by at least 0.015, which comprises fractionally extracting said viscous oil with ethyl acetoacetate.

19. The process of treating a viscous mineral oil of viscosity-gravity constant higher than 0.850 to produce an oil having a viscosity-gravity constant less than 0.830 which comprises fractionally extracting said viscous oil with ethyl acetoacetate.

20. The process of treating a viscous mineral oil of viscosity-gravity constant higher than 0.835 to produce an oil having a viscosity-gravity constant of less than 0.828 which comprises fractionally extracting said viscous oil with ethyl acetoacetate.

SEYMOUR W. FERRIS. 

